#include "apue.h"

static volatile sig_atomic_t sigflag; /* set nonzero by sig handler */
static sigset_t newmask, oldmask, zeromask;

static void sig_usr(int signo) /* one signal handler for SIGUSR1 and SIGUSR2 */ { sigflag = 1; }

void TELL_WAIT(void)
{
    if (signal(SIGUSR1, sig_usr) == SIG_ERR)
        err_sys("signal(SIGUSR1) error");
    if (signal(SIGUSR2, sig_usr) == SIG_ERR)
        err_sys("signal(SIGUSR2) error");
    sigemptyset(&zeromask);
    sigemptyset(&newmask);
    sigaddset(&newmask, SIGUSR1);
    sigaddset(&newmask, SIGUSR2);

    /*
     * Block SIGUSR1 and SIGUSR2, and save current signal mask.
     */
    if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)
        err_sys("SIG_BLOCK error");
}

void TELL_PARENT(pid_t pid) { kill(pid, SIGUSR2); /* tell parent we're done */ }

void WAIT_PARENT(void)
{
    while (sigflag == 0)
        sigsuspend(&zeromask); /* and wait for parent */
    sigflag = 0;

    /*
     * Reset signal mask to original value.
     */
    if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        err_sys("SIG_SETMASK error");
}


void TELL_CHILD(pid_t pid) { kill(pid, SIGUSR1); }

void WAIT_CHILD(void)
{
    while (sigflag == 0)
        sigsuspend(&zeromask); /* and wait for child */
    sigflag = 0;

    /*
     * Reset signal mask to original value.
     */
    if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        err_sys("SIG_SETMASK error");
}